1. Field of the Invention
The present invention relates to a photographic film cassette, more specifically to an apparatus and method for loading photographic film into the cassette and removing photographic film from the cassette.
2. Description of the Related Art
Photographic film of the 135 type, contained in a cassette, is among the most popular formats of photographic film. A known 135 photographic film cassette has a cassette shell constituted of a cylindrical body and formed in a thin metal sheet two caps, fitted thereon. The cassette has a spool contained in the cassette shell on which photographic film is wound in a form of a roll. To assemble this photographic film cassette, several methods are known. For example, U.S. Pat. No. 4,614,019 (corresponding to Japanese Patent Publication No. 2-691) discloses a process of winding the photographic film on the spool, and then assembling the cassette in a darkroom; U.S. Pat. No. 4,080,711 (corresponding to Japanese Patent Publication No. 60-48748) discloses a process of bringing the assembled cassette shell into the darkroom, disassembling the cassette shell for insertion of the photographic film, inserting the photographic film wound on the spool, and then assembling the cassette shell.
U.S. Pat. No. 3,910,516 (corresponding to Japanese Patent Laid-open Publication No. 49-107732) and Japanese Patent Laid-open Publication No. 52-77723 also disclose a photographic film cassette producing method wherein an empty spool is loaded by inserting a tongue-like guide plate into a photographic film passage port formed in the cassette, then inserting a trailer of photographic film into the cassette while it is guided along the guide plate. The trailer is then fixed to the spool and the spool is rotated to wind the photographic film up into the cassette.
U.S. Pat. No. 4,834,306, U.S. Pat. No. 4,846,418 and European Publication EP-A2 0 406 815 (corresponding to Japanese Patent Laid-open Publication No. 3-37645), each disclose a photographic film cassette in which a cassette shell is constituted of parts formed from resin, and rotation of a spool causes a leader of the photographic film to exit to the outside of the cassette. Such a leader-advancing cassette is different from photographic film cassettes conventionally in use because the leader of the photographic film is fully contained within the cassette both before exposure and after exposure. Such a cassette is advantageous in that the photographic film is reliably protected from accidental exposure to ambient light, and in that the cassette is easily handled.
Generally, a leader advancing cassette including elements not utilized in conventional cassettes. For example, the cassette shell of such a device can incorporate a light-shielding shutter member arranged openably in the photographic film passage port for projecting the inside from ambient light, or a visual indicator member arranged to appear externally for indicating the exposed condition of the photographic film. However, production of such a leader-advancing cassette has many inherent problems due to the increase in the number of the parts. Particularly, the assembling operation is difficult and must be accomplished in the darkroom. Accordingly, problems arise in inspection, maintenance, and safety during the manufacturing operation.
When a leader-advancing cassette is produced by above-mentioned method disclosed in U.S. Pat. No. 3,910,516 and Japanese Patent Laid-open Publication No. 52-77723, although the guide plate is first inserted for inserting the trailer into the cassette, there is strong possibility that the trailer in the course would become flexed or bent before reaching the spool and thus is not positively fixed to the spool.
Also, after effecting exposure on the photographic film, the exposed photographic film is removed from the cassette for a developing process. Although the photographic film is drawn out of the cassette, the photographic film cannot be separated from the spool because the trailer of the photographic film is fixedly retained on the spool. To remove the photographic film from the cassette, it is conventional to cut off the photographic film while leaving a portion of the trailer within the cassette.
Recently, recycling photographic film cassettes has become popular. The recycling includes: reusing parts after the first use; and remolding new resinous parts by melting the use resinous parts. It is, however, difficult to reuse such a used cassette, because the trailing portion of the photographic film is irremovably attached on the spool. To remold a resinous cassette from a cassette containing a small portion of the photographic film degrades the quality of the resin to be molded, because the small portion of the photographic film is mixed in the resin. Therefore the cassette, after separation of the photographic film, must be disassembled to remove the small portion of the photographic film from the spool. Also, the small portion of the film must then be properly disposed of.